JP3046729B2 - Rotating head type magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type magnetic recording / reproducing apparatus, and more particularly to a rotary head type magnetic recording / reproducing apparatus having an actuator for dynamic tracking of a helical scan type video tape recorder. is there.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus, recording density has been remarkably increased, and the track width has been narrowed accordingly. For example, in the LP mode of a home digital VTR, the track pitch is 5
μm. With such a narrow track width,
The conditions required for a magnetic head to perform a good tracking operation are becoming stricter. That is, when a signal is reproduced from a narrow track by a conventional magnetic recording / reproducing device fixed to a rotating drum so that the magnetic head cannot move in the track width direction, the influence of the tracking deviation of the magnetic head is affected. Appears prominently. As a result, a sufficient reproduction output cannot be obtained from the magnetic head.

As a factor of such a tracking deviation, a so-called track bend generated at the time of recording can be considered. This track bend is unique to each magnetic recording / reproducing device. Therefore, especially when the track is reproduced by a magnetic recording / reproducing apparatus different from the apparatus used for recording, the deviation of the tracking due to the curve of the track becomes a magnitude that cannot be ignored. Therefore, at the time of reproduction, it is necessary to cause the magnetic head to follow the track bending, that is, to perform a dynamic tracking operation. Hereinafter, a conventional rotary head type magnetic recording / reproducing apparatus equipped with this dynamic tracking actuator will be described.

FIGS. 22 and 23 correspond to Japanese Patent Publication No. 5-8486.
FIG. 1 is a cross-sectional view and an exploded perspective view schematically showing the configuration of a rotary head type magnetic recording / reproducing apparatus equipped with a mechanism similar to the moving magnet type dynamic tracking mechanism disclosed in Japanese Unexamined Patent Publication (Kokai) Publication.

Referring to FIGS. 22 and 23, a rotary head type magnetic recording / reproducing apparatus 800 includes a fixed drum 830.
And a rotating shaft 82 rotatably supported by two bearings 823 provided on a boss of the fixed drum 830.
1, a rotating drum 840 supported so as to be rotatable integrally with the rotating shaft 821, a dynamic tracking mechanism, and rotary transformers 831 and 833.

The dynamic tracking mechanism includes magnetic heads 801a and 801b and head bases 803a and 803a.
03b, parallel leaf springs 805a, 805b, permanent magnet 8
07a, 807b, fixing members 811, 811, yokes 813a, 813b, and a coil 815.

A first leaf spring 805 constituting a parallel leaf spring
a is fixed to the rotating drum 840 by fixing members 811 and 811 (FIG. 23). Further, the second leaf spring 805b constituting the parallel leaf spring is also supported by the rotating drum 840 by sandwiching the fixing members 811 and 811 with the first leaf spring 805a.

The yokes 813a and 813b are
1 so as to be opposed to each other with the first plate spring 805 interposed therebetween.
b. The yokes 813a, 813
b is made of a soft magnetic material. Permanent magnet 807a,
Each of the 807b is attached to a surface of the yokes 813a and 813b on the rotation shaft 821 side. The permanent magnet 807a and the yoke 813a function as a movable member 808a of the parallel leaf springs 805a and 805b, and the permanent magnet 807b and the yoke 813b function as a movable member 808b.

Each of the magnetic heads 801a, 801b
Movable member 8 with head bases 803a and 803b interposed
08a, 808b. Magnetic head 80
1a and 801b are arranged so as to face the outer peripheral surfaces of the fixed drum 830 and the rotating drum 840.

[0010] The drive coil 815 is provided on the outer periphery of the stator 836 of the fixed drum 830 with each permanent magnet 807a, 807b.
And are wound so as to face each other at a predetermined distance.
The stator 836 is made of a soft magnetic material yoke, and includes permanent magnets 807a and 807b and yokes 813a and 813b.
Together, they constitute a magnetic circuit.

Next, the magnetic heads 801a and 801a
A description will be given of the vibration characteristics of the actuator in the case where 01b is supported by the parallel leaf springs 805a and 805b.

FIGS. 24 and 25 are schematic diagrams showing the vibration characteristics of the magnetic head supported by the parallel leaf springs as described above. FIG. 24 is a diagram of the magnetic head 801a with respect to the supply current (input) to the drive coil 815. 22 shows the frequency response of the displacement (output) in the Z direction in 22. Specifically, FIG.
4 is a graph showing a relationship between frequency and gain, and FIG. 25 is a graph showing a relationship between frequency and phase.

Referring to FIGS. 24 and 25, since magnetic head 801a is supported by parallel leaf springs 805a and 805b, a higher-order resonance point exists in the vibration characteristics of the magnetic head. Further, in this configuration, among the above-described higher-order resonance points, rotational vibration in the RY direction in FIG.

FIG. 24 shows an example in which this rotational vibration appears as a secondary resonance point. That is, the primary resonance point (frequency f ₁ ) corresponds to the vibration in the Z direction in FIG.
The secondary resonance point (frequency f ₂ ) corresponds to the rotational vibration in the RY direction in FIG. In such a configuration, R
The center of rotation in the Y direction substantially coincides with the center of gravity of the movable member 808a. In FIGS. 24 and 25, the third and higher order resonance points are omitted.

Next, the general operation of the drum device shown in FIG. 22 during signal recording and signal reproduction will be described.

[At the time of signal reproduction] FIG. 26 is a control block diagram of closed loop control at the time of signal reproduction. Referring to FIG. 26, the signal input to amplifier 850 is input to drive coil 815 through phase compensation circuit 851 and driver 852. That is, the drive coil 815 is energized.

The permanent magnet 807a is arranged so that its magnetic flux links with the drive coil 815. For this reason,
When the drive coil 815 is energized, a vertical drive force acts on the permanent magnet 807a according to Fleming's left-hand rule. As a result, the movable member 808a including the permanent magnet 807a applies this driving force to the parallel leaf springs 805a, 805.
It is displaced to a position where the reaction force of b is balanced. Therefore,
By applying a control current to the drive coil 815, the height of the magnetic head 801a attached to the movable member 808a can be controlled.

Here, the height information of the magnetic head is detected from a pilot signal reproduced by the magnetic head. The information thus obtained is the position of the magnetic head relative to the track on the magnetic tape. In this detection method, at the time of signal recording, a pilot signal having a different frequency for each track is recorded in advance so as to be superimposed on the main signal. During signal playback,
The magnetic head extracts pilot signal components from tracks adjacent to both sides of the track to be scanned, and compares the components to detect a relative position with respect to the track to be scanned. By feeding back this information, the magnetic head can follow the track. Thus, the dynamic tracking operation is performed.

The signals of the magnetic head are transmitted by the rotary transformers 831 and 833.

[During Signal Recording] At the time of signal recording, the dynamic tracking operation is not performed and the parallel leaf spring 805 is used.
a, 805b due to the rigidity of the magnetic heads 801a, 801b.
b is supported.

[0021]

When a rubber member is used as a member for supporting a magnetic head on a rotating drum, the mechanical properties (Young's modulus and viscosity coefficient) of the rubber member change with time and with temperature. It becomes difficult to control the accuracy.

Therefore, in order to facilitate high-precision control, in the conventional rotary head type magnetic recording / reproducing apparatus as described above, a parallel leaf spring 805a is used as a magnetic head displacement means.
805b is used. However, the parallel leaf spring 805
a and 805b, the conventional rotary head type magnetic recording / reproducing apparatus has the following problems.

(1) The responsiveness of the dynamic tracking operation during signal reproduction is poor. (2) The magnetic head vibrates during signal recording.

Hereinafter, the problem will be described in detail. (1) Responsiveness of the dynamic tracking operation In recent years, the number of rotations of the drum tends to increase with an increase in data transfer speed and a reduction in the diameter of the drum. For example,
In a home digital VTR, the number of rotations of the drum is 9
000 rpm. When the rotation speed of the drum is high as described above, the response frequency of dynamic tracking must be increased in order to follow the track bending.

FIG. 27 is a graph showing the relationship between frequency and gain of the open loop transfer function in the block diagram of FIG. 26, and FIG. 28 is a graph showing the relationship between frequency and phase. Here, the input is point M in FIG. 26, and the output is point N.

Referring to FIGS. 27 and 28, a conventional rotation
In a head type magnetic recording / reproducing device, the magnetic
Because the head is supported, its vibration characteristics
There is a resonance point. Here, the order of the frequency at which the primary resonance occurs
Phase delay can be avoided by phase compensation (Figure 26)
Noh. In contrast, the frequency f at which the secondary resonance occurs _Two
In the vicinity, it is difficult to avoid the phase delay, and about 18
A phase delay of 0 ° occurs. That is, the phase is delayed by 180 °
Frequency (phase intersection frequency) f₀Is the secondary resonance frequency f_Two
(F₀≒ f_Two).

In general, oscillation occurs when the phase is delayed by about 180 ° and the gain is 0 dB. Therefore, the peak at the secondary resonance point where a phase delay of about 180 ° must be located below the gain of 0 dB to secure a gain margin.

Due to such restrictions, the gain intersection frequency f _C, which is the intersection of the gain-frequency curve and the gain of 0 dB, is obtained.
Is determined. If the frequency is equal to or lower than the gain intersection frequency f _C , the operation of the magnetic head can be controlled. That is, the response frequency of the dynamic tracking is represented by the gain intersection frequency f _C.

The gain-frequency curve in FIG. 27 can be moved up and down in the figure by adjusting the gain of the amplifier. However, the above-described restrictions limit the gain adjustment of the amplifier, and consequently limit the gain crossover frequency f _C , that is, the dynamic tracking response frequency. For this reason, when the rotation speed of the drum is higher,
It cannot follow the track bend, and the responsiveness of the dynamic tracking operation deteriorates.

Therefore, the gain intersection frequency f _{C in} FIG.
(Dynamic tracking response frequency) is desired to be high. As a method of increasing the gain intersection frequency f _C , there is a method of increasing the secondary resonance frequency f ₂ or a method of decreasing the peak value (gain value) at the secondary resonance point f ₂ .

[0031] That is, the secondary resonance frequency as shown in FIG. 29 A higher from f ₂ to f _21, the gain - for the frequency curve can be adjusted to the upward in the drawing, the gain crossover frequency f _C
To f _C1 . When the peak value at the secondary resonance point decreases as shown in FIG. 30, the gain intersection frequency can be similarly increased from f _C to f _C2 .

Referring to FIG. 22, parallel leaf spring 805
In the optimization of the designs a and 805b, there is a limit to maintaining the primary resonance frequency and increasing the secondary resonance frequency, including restrictions on space. Therefore, in order to significantly increase the secondary resonance frequency, the primary resonance frequency must also be increased. To increase the primary resonance frequency,
It is necessary to increase the rigidity of the parallel leaf springs 805a and 805b in the Z direction or reduce the mass of the movable parts 808a and 808b.

However, the parallel leaf springs 805a, 805b
When the stiffness is increased, the primary and higher resonance frequencies are increased, but the parallel leaf springs 805a and 805b are less likely to be displaced in the Z direction. For this reason, unless the driving force of the magnetic head is increased, it is impossible to obtain a displacement amount equivalent to that of the related art.

When the size of the permanent magnets 807a and 807b is reduced in order to reduce the mass of the movable portions 808a and 808b, the magnetic flux linked to the drive coil 815 decreases. As a result, the driving force is reduced, and a displacement equivalent to that of the related art cannot be obtained.

As described above, in order to increase the primary and higher resonance frequencies while securing the same amount of displacement as in the prior art, the driving force must be increased. However, in order to increase the driving force in the configuration shown in FIG. 22, it is necessary to supply a large current to the driving coil 815, which increases power consumption and heat generation.

To lower the peak of the secondary resonance point,
It is necessary to reduce the RY-direction moment generated by the driving force acting on the permanent magnets 807a and 807b. To reduce the RY direction moment due to this driving force,
The point of application of the driving force is set at the rotation center (movable members 808a, 808).
b). However, in the configuration shown in FIG. 22, the driving force acts on only one of the magnetic poles of the permanent magnets 807a and 807b. For this reason, the permanent magnets 807a and 807a
The point of application of the driving force cannot be made closer to the center of rotation unless the radial thickness of the 07b and the yokes 813a and 813b is reduced. However, the permanent magnets 807a, 80
In order to reduce the thickness in the radial direction such as 7b, there are naturally limitations in processing and assembly. From such a limit, the permanent magnet 807a,
It is difficult to reduce the thickness in the radial direction such as 807b,
Therefore, it has been difficult to reduce the moment in the RY direction due to the driving force.

As described above, it is very difficult to increase the secondary resonance frequency and lower the peak value at the secondary resonance point in the configuration shown in FIG. Therefore, when the rotation speed of the drum is higher, it is impossible to follow the track bend, and the responsiveness of the dynamic tracking operation is deteriorated.

(2) Vibration of Magnetic Head During Signal Recording Referring to FIG. 22, to suppress the vibration of the magnetic heads 801a and 801b, it is effective to increase the rigidity of the parallel leaf springs 805a and 805b. . However, the parallel leaf spring 8
05a, 805b, the parallel leaf spring 80
5a and 805b are hardly deformed, and unless the driving force is increased, the same amount of displacement as in the related art cannot be obtained. FIG.
In order to increase the driving force in the configuration shown in FIG.
It is necessary to supply a large current to the power supply 15 and power consumption and heat generation increase. Therefore, it has been difficult to prevent the magnetic head from vibrating during signal recording while maintaining low power consumption and heat generation.

When a rubber member (damper member) is used as the magnetic head displacement means, the peak of the resonance point of the rubber member is much smaller than that of the parallel leaf spring. Almost no need.

Therefore, one object of the present invention is to improve the responsiveness of a dynamic tracking operation during signal reproduction.

Another object of the present invention is to suppress vibration of the magnetic head during signal recording.

In the conventional example shown in FIG. 22, each member is attached at the time of assembling the rotary head type magnetic recording / reproducing apparatus (for example, attaching the magnetic heads 801a, 801b to the head bases 803a, 803b, the head base 803).
a, 803b attached to movable members 808a, 808b, rotating drum 840 of parallel leaf springs 805a, 805b
To the drive coil 815, an error occurs in the height of the magnetic heads 801a and 801b when no current is supplied.

If the height of the magnetic heads 801a and 801b from the reference (hereinafter referred to as absolute height) deviates from a predetermined height (hereinafter referred to as reference height), recording and reproduction can be performed in a predetermined tape format. And compatibility between devices cannot be obtained. Also, two magnetic heads 801a and 801b
If the relative height (hereinafter referred to as a relative height) differs from the above, signals cannot be recorded at a predetermined track pitch.

A configuration for solving this problem is disclosed in
-52532 and JP-A-4-121814. Note that, in both the above publications, the configuration of the dynamic tracking operation is different from the conventional technology shown in FIGS. 22 and 23.

Japanese Patent Publication No. Sho 61-52532 discloses a moving magnet mechanism for performing a seesaw operation. That is, a seesaw operation is performed on two sets of magnetic heads by supplying a DC bias current to the drive coil, thereby adjusting the relative heights of the two sets of magnetic heads.

However, with the above configuration, the absolute height of the magnetic head cannot be adjusted. Further, in addition to the displacement required for the dynamic tracking operation by the magnetic head displacement means, the displacement required for absorbing the relative height error due to the mounting of the magnetic head must be secured. Therefore, an extra driving force is required, power consumption is increased, and the amount of heat generated by the driving coil is increased. Further, when the above configuration is used as it is, the magnetic head tilts with the displacement due to the seesaw operation, so that the hit between the tape and the head deteriorates.

JP-A-4-121814 discloses a dynamic tracking mechanism using a bimorph plate. That is, it is shown that the height of the magnetic head is adjusted by pressing the support member downward with a screw while applying an upward driving force to the magnetic head support member made of a bimorph plate. At the time of signal recording, the magnetic head supporting member is provided with an upward driving force and comes into contact with the screw. Further, the dynamic tracking operation at the time of signal reproduction is performed in a state where the magnetic head supporting member is separated from the screw.

However, even if the above configuration is applied to the above-mentioned conventional technology (FIGS. 22 and 23), a large driving force must be supplied at the time of signal recording, and power consumption increases.
Further, in consideration of the processing accuracy of the magnetic head support member and the screw, and the change over time of the contact state, reproducibility cannot be obtained in the height of the magnetic head during signal recording. In other words, it is not possible to adjust the temporal deviation of the height of the magnetic head during signal recording.

As described above, conventionally, it has been difficult to adjust the height of the magnetic head. Therefore, still another object of the present invention is to easily adjust the height of a magnetic head.

[0050]

According to a first aspect of the present invention, there is provided a rotating head type magnetic recording / reproducing apparatus comprising: a fixed drum;
It includes first and second leaf springs, a magnetic head, a movable member, a yoke, and first and second coils. The stationary drum has an axis. The rotating body includes a rotating drum supported on a fixed drum so as to be rotatable about an axis. The first and second leaf springs have a movable part and a fixed part, and the fixed part is supported by the rotating body so that the movable part can be displaced in a direction along the axis. The first and second leaf springs face each other at a predetermined distance. The magnetic head is fixed to the movable portion of the first leaf spring. The movable member includes a permanent magnet having first and second magnetic poles sandwiched between the movable portion of the first leaf spring and the movable portion of the second leaf spring. The yoke has a first side and a second side, and the first side faces the first pole of the permanent magnet with a predetermined space therebetween, and the second side faces the second side of the permanent magnet. It is arranged on the fixed drum so as to face the magnetic pole with a predetermined space therebetween. The first coil is fixedly provided so as to face the first magnetic pole of the permanent magnet with a predetermined space therebetween. The second coil is fixed so as to face the second magnetic pole of the permanent magnet with a predetermined space therebetween. The permanent magnet and the first and second coils are arranged so that the magnetic head moves in the direction along the axis by energizing the first and second coils.

In the rotating head type magnetic recording / reproducing apparatus according to the second aspect, the first and second leaf springs have a configuration of supporting beams at both ends. Both ends of the first and second leaf springs are fixed portions. A central portion sandwiched between both ends of the first and second leaf springs is a movable portion.

In the rotary head type magnetic recording / reproducing apparatus according to the third aspect, the yoke has an annular shape centered on the axis.

In the rotary head type magnetic recording / reproducing apparatus according to the fourth aspect, the movable member has a shield plate made of a soft magnetic material. The first leaf spring has a first surface and a second surface located on the back surface of the first surface. The magnetic head is supported on a first surface of the first leaf spring. The permanent magnet is supported on the second surface of the first leaf spring via a shield plate.

In the rotary head type magnetic recording / reproducing apparatus according to the fifth aspect, the yoke has an arc shape centered on the axis.

In the rotary head type magnetic recording / reproducing apparatus according to the sixth aspect, the magnetic tape is wound around the outer peripheral surfaces of the rotary drum and the fixed drum. In a section where the magnetic head scans the magnetic tape during one rotation of the magnetic head, at least each of the first and second magnetic poles of the permanent magnet is separated from the first and second side surfaces of the yoke by a predetermined space. The center angle of the yoke having an arc shape is set so as to be opposed to each other.

The rotary head type magnetic recording / reproducing apparatus according to claim 7 further includes a leaf spring pressing member and a head height adjusting member. The leaf spring pressing member is the first or second
The leaf spring is supported by a rotating body such that an intermediate portion between the movable portion and the fixed portion can be pressed in a direction along the axis. The head height adjusting member is sandwiched between an intermediate portion of the first leaf spring and an intermediate portion of the second leaf spring.

A rotary head type magnetic recording / reproducing apparatus according to claim 8, wherein the fixed drum, the rotating body, the first and second leaf springs, the magnetic head, the movable member, the driving means, and the leaf spring It has a pressing member and a head height adjusting member.
The fixed drum is centered on the axis. The rotating body includes a rotating drum supported on a fixed drum so as to be rotatable about an axis. The first and second leaf springs
It has a movable part and a fixed part, and the fixed part is supported by the rotating body so that the movable part can be displaced in the direction along the axis. The first and second leaf springs face each other at a predetermined distance. The magnetic head is fixed to the movable portion of the first leaf spring. The movable member is sandwiched between the movable portion of the first leaf spring and the movable portion of the second leaf spring. The driving means displaces the movable portions of the first and second leaf springs in a direction along the axis. The leaf spring pressing member is supported by the rotating body such that an intermediate portion between the movable portion and the fixed portion of the first or second leaf spring can be pressed in a direction along the axis. The head height adjusting member is sandwiched between an intermediate portion of the first leaf spring and an intermediate portion of the second leaf spring.

In the rotary head type magnetic recording / reproducing apparatus according to the ninth aspect, the distance between the intermediate portion and the fixed portion of the leaf spring pressed by the leaf spring pressing member is equal to the distance between the intermediate portion and the movable portion. Shorter than.

According to a tenth aspect of the present invention, there is provided a rotary head type magnetic recording / reproducing apparatus, wherein the leaf spring pressing member presses the axis of the portion between the intermediate portion and the fixed portion of the leaf spring in the radial direction of the rotating surface. The width is wider than the radial width of the portion between the intermediate part and the movable part.

In the rotary head type magnetic recording / reproducing apparatus according to the eleventh aspect, the width of the first leaf spring in the radial direction of the rotation surface about the axis is larger than the width of the second leaf spring in the radial direction. wide.

A rotary head type magnetic recording / reproducing apparatus according to a twelfth aspect has a magnetic head group composed of one or a plurality of magnetic heads and two movable members each including a permanent magnet. Each one of the two sets of magnetic head groups is provided corresponding to each one of the two sets of movable members. In both of the two sets of permanent magnets, when the magnetic pole closer to the axis is the first magnetic pole and the magnetic pole farther from the axis is the second magnetic pole, the first permanent magnet corresponding to one magnetic head group is used. And the first magnetic poles of the permanent magnets corresponding to the other magnetic head group have different polarities, and the second magnetic poles of the permanent magnets corresponding to the one magnetic head group and the other magnetic head group The two permanent magnets are configured such that the second magnetic poles of the permanent magnets corresponding to are different from each other. First and second
The two sets of permanent magnets and the first and second coils are arranged so that the two sets of magnetic head groups are displaced in opposite directions by energizing the first set of coils.

[0062]

In the rotary head type magnetic recording / reproducing apparatus according to the first to third aspects, the first and second coils are provided so as to face both sides of the permanent magnet. , A driving force can be applied. Therefore, a larger driving force can be obtained than in the conventional example in which the driving force is applied only to one surface of the permanent magnet. Since the driving force is large, the parallel leaf spring can be sufficiently displaced even if the rigidity of the parallel leaf spring is increased. Therefore, it is possible to increase the first and higher order resonance frequencies, and the responsiveness of dynamic tracking is improved.

Since the rigidity of the leaf spring can be increased, vibration of the magnetic head during recording can be suppressed.

Further, since the yoke constituting the magnetic circuit is arranged on the fixed drum, the mass of the movable portion of the parallel leaf spring can be reduced as compared with the conventional example in which the yoke is supported by the parallel leaf spring. Therefore, it is possible to increase the primary and higher resonance frequencies, and the responsiveness of dynamic tracking is further improved.

Further, since a driving force can be applied to both side surfaces of the permanent magnet, by making the driving forces acting on both side surfaces equal, a rotational moment can be applied to the movable portion of the parallel leaf spring. Is prevented. For this reason, the peak value of the gain at the rotational resonance can be reduced, and the responsiveness of the dynamic tracking is further improved.

In the rotary head type magnetic recording / reproducing apparatus according to the fourth aspect, the permanent magnet is attached to the leaf spring via a shield plate. Since this shield plate is made of a soft magnetic material, magnetic flux leakage from the permanent magnet is absorbed by the shield plate. Therefore, the magnetic flux leaked from the permanent magnet does not affect the magnetic head.

In the rotating head type magnetic recording / reproducing apparatus according to the fifth and sixth aspects, the yoke has an arc shape,
It is not provided over the entire circumference. For this reason, a space is obtained in the fixed drum as compared with the case where the yoke is provided over the entire circumference. By utilizing this space, it is possible to achieve more functions and higher functions while maintaining the dimensions.

In the rotary head type magnetic recording / reproducing apparatus according to the present invention, the absolute height of the magnetic head at the time of assembling the drum device can be adjusted by pressing a predetermined position of the leaf spring with the leaf spring pressing member. It becomes possible.

In the rotary head type magnetic recording / reproducing apparatus according to the eleventh aspect, the first leaf spring constituting the parallel leaf spring is wider in the radial direction than the second leaf spring. Therefore, when assembling the drum device, the magnetic head can be easily attached to the first leaf spring. Further, since the width of the first leaf spring in the radial direction is wide, the rigidity of the first leaf spring is improved, and the vibration of the magnetic head can be suppressed.

In the rotary head type magnetic recording / reproducing apparatus according to the twelfth aspect, the magnetization directions of the two permanent magnets are opposite. Therefore, by supplying a DC bias current to the drive coil, the magnetic head group at a relatively high position is displaced downward, and the magnetic head group at a relatively low position is displaced upward, so that two sets of magnetic heads are displaced. The relative height of the head group can be adjusted.

[0071]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a perspective view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to Embodiment 1 of the present invention. FIG. 2 is a perspective view of a main part of the rotary head type magnetic recording and reproducing apparatus according to the first embodiment of the present invention. FIG. 3 is a plan view seen from the direction of arrow X in FIG. 2, and FIG. 4 is a plan view of the head bases 3a and 3b, the magnetic heads 1a and 1b of FIG.
FIG. 4 is a plan view omitting a leaf spring 5a. FIGS. 5 and 6 are schematic sectional views of a rotary head type magnetic recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 5 corresponds to a cross section taken along line BB of FIGS. 3 and 4, and FIG. 6 corresponds to a cross section taken along line CC of FIGS. 3 and 4. .

Referring first to FIG. 1, in a rotary head type magnetic recording / reproducing apparatus 100 of the present embodiment, a shaft 2 having an axis AA is provided at the center of a cylindrical fixed drum 30.
1 is fixed. This shaft 21 has an axis A-A
Cylindrical rotating drum 4 so as to be rotatable around
0 is supported.

Referring mainly to FIGS. 5 and 6, the rotating drum 40 is mounted on a disk 35, and the disk 35 is mounted on the outer periphery of a pair of upper and lower outer bearings 23.

The fixed drum 30 arranged as described above,
A motor, a rotary transformer, and a dynamic tracking mechanism are mainly attached to the rotating drum 40 and the shaft 21.

Referring to FIGS. 5 and 6, the motor has a rotor 25 and a stator 27. The rotor 25
The stator 27 is attached to the rotating drum 40,
It is attached to the shaft 21. The motor composed of the rotor 25 and the stator 27 causes the rotating drum 40 to
A driving force for rotation is provided.

The rotary transformer has a stator core 31 and a rotor core 33. The rotor core 33 is attached to the rotating drum 40, and the stator core 31 is attached to the fixed drum 30.

Referring mainly to FIGS. 3 to 6, the dynamic tracking mechanism comprises magnetic heads 1a and 1b, head bases 3a and 3b, parallel leaf springs 5a and 5b, permanent magnets 7a and 7b, and spacers. 9a, 9b and fixing member 11
a, 11b, yoke 13 and drive coils 15a, 15b
And

Referring mainly to FIG. 7, first and second leaf springs 5a and 5b constituting a parallel leaf spring have a ring shape. Between the first and second leaf springs 5a, 5b, there are movable members 8a, 8b and fixed members 11a, 11b.
Is pinched. The movable members 8a and 8b are arranged to face each other, and the fixed members 11a and 1b
1b are arranged so as to face each other. The movable members 8a and 8b are respectively composed of the permanent magnets 7a and 7b and the spacer 9
a, 9b. This spacer 9
a and 9b are made of a non-magnetic material.

Referring mainly to FIG. 6, parallel leaf springs 5a, 5a
b is fixed to the rotating drum 40 at a portion where the fixing members 11a and 11b of the first leaf spring 5a are attached.

Referring mainly to FIGS. 5 and 6, in this state, the portions of the parallel leaf springs 5a and 5b where the movable members 8a and 8b are attached are the portions where the fixed members 11a and 11b are attached. It can be displaced as a fixed end. That is, the movable members 8a and 8b of the parallel leaf springs 5a and 5b have a configuration like a movable portion of a support beam at both ends.

Referring mainly to FIGS. 3 and 5, a portion of the first leaf spring 5a to which the movable members 8a and 8b are attached,
The magnetic head 1 is interposed between the head bases 3a and 3b.
a, 1b are attached. These magnetic heads 1
“a” and “1b” are arranged such that their tips face the outer peripheral surfaces of the fixed drum 30 and the rotating drum 40.

Referring mainly to FIGS. 3 to 6, yoke 13
Has a ring shape having a concave cross section, and has a fixed drum 3
0 is attached. Further, the yoke 13 includes first and second side surfaces 13a and 13b constituting each side surface of the concave portion.
have. This first side surface 13a is a permanent magnet 7a,
One side 7a _1, 7b ₁ and predetermined so as to face with a space, and the second side surface 13b is a permanent magnet 7a in 7b,
So as to face at a second side surface 7a _2, 7b ₂ with a predetermined space 7b, the yoke 13 is disposed on the stationary drum 30.

One side surfaces 7a ₁ , 7a of permanent magnets 7a, 7b
A _first drive coil 15a is wound around the first side surface 13a of the yoke 13 so as to face b1 with a predetermined space therebetween. Also, the other side surface 7a ₂ of the permanent magnets 7a, 7b,
A _second drive coil 15b is wound around the second side surface 13b of the yoke 13 so as to face the second drive coil 7b2 with a predetermined space therebetween.

The yoke 13 includes the permanent magnets 7a, 7b
Together, they constitute a magnetic circuit. Referring mainly to FIG. 6, terminals 43 a and 43 b for connecting to a drive coil are provided on fixed drum 30 via terminal block 41. Further, terminals 39 a and 39 b connected to the windings of the stator core 31 of the rotary transformer are provided on the fixed drum 30 via the terminal block 37. The driving coils 15a, 1
There are a plurality of terminals 43a and 43b connected to 5b, including those not shown. Further, the drive coils 15a, 15
b may be connected to each other.

The stator core 3 of the rotary transformer
1 is disposed below the yoke 13 to reduce the radius of the fixed drum 30.

The fixing members 11a and 11b are fixed to the rotating drum 40.
May be fixed.

Further, in this example, one magnetic head is attached to one movable member, but a plurality of magnetic heads may be attached to one movable member. The spacers 9a and 9b are necessary in terms of space because the magnetic heads 1a and 1b are fixed to the lower surfaces of the head bases 3a and 3b in the drawing. Therefore, for example, when the magnetic heads 1a and 1b are fixed to the upper surfaces of the head bases 3a and 3b in the drawing, the spacers 9a and 9b may not be provided.

Although the example of the drum device of the fixed shaft type is shown here, the form of the drum device is not limited to this, and a drum device of a shaft rotating type may be used.

Next, a method of assembling the rotary head type magnetic recording / reproducing apparatus of this embodiment will be described.

Referring mainly to FIG. 5 and FIG.
5 rotatably supports the fixed drum 30
It is fixed by a method such as press-fitting and heat shrinking. Thereafter, the rotating drum 40 is fixed on the disk 35 rotatable with respect to the shaft 21. In this state, the rotating drum 40 is rotatably held with respect to the fixed drum 30. Next, the rotor 25 of the motor is fixed to the upper surface of the rotating drum 40,
A collar 29 is fixed to the shaft 21. Finally, the stator 27 of the motor is fixed to the collar 29.

In the above configuration, the rotating drum 40 substantially integral with the rotor 25 of the motor is rotated by the rotational driving force of the motor with respect to the fixed drum 30 substantially integral with the stator 27 of the motor. .

Next, the basic operation of the tracking actuator in the rotary head type magnetic recording / reproducing apparatus of this embodiment will be described. Since the operations of the magnetic head 1a and the magnetic head 1b are the same, here, the magnetic head 1
Only the operation a will be described.

FIG. 8 is a schematic sectional view showing a part of the section of FIG. 5 in an enlarged manner. 5 and 8, as described above, the fixing members 11a, 11b of the parallel leaf springs 5a, 5b
The portion to which the movable member 8a is attached can be displaced in the vertical direction in the figure, with the portion to which is attached as a fixed end. The magnetic head 1a is mounted on a portion of the leaf spring 5a to which the movable member 8a is mounted via a head base 3a. For this reason, the magnetic head 1a can be displaced in the vertical direction (the direction perpendicular to the rotation plane) in the figure.

The permanent magnet 7a has, for example, one side surface 7a.
a₁Is the N pole, the other side surface 7a_TwoIn the radial direction so that
It is magnetized. Both sides 7a of this permanent magnet 7a₁,
7a _TwoAre the side surfaces 13 of the yoke 13 having a concave cross section.
a and 13b are opposed by a predetermined space.
A magnetic circuit is configured. In addition, the first and second yoke 13
The drive coils 15 are provided on the side surfaces 13a and 13b of the
a, 15b interlink with the magnetic flux generated by the permanent magnet 7a
It is provided as follows.

Here, when currents in the same direction are supplied to the two drive coils 15a and 15b through the terminals 43a and 43b, the electromagnetic force fa ₁ from the drive coil 15a is applied to one side surface 7a ₁ of the permanent magnet 7a. , The other side 7a ₂
Electromagnetic force fa ₂ from the drive coil 15b respectively act on. Note the orientation of the action of the electromagnetic force fa ₁ and fa ₂ are the same.

The parallel leaf springs 5a and 5b are displaced to a position where the electromagnetic force fa (= fa ₁ + fa ₂ ) acting on the permanent magnet 7a and the reaction force of the parallel leaf springs 5a and 5b are balanced. With the displacement of the parallel leaf springs 5a, 5b, the magnetic head 1a
Also displaces.

As described above, by supplying the control current to the drive coils 15a and 15b, the magnetic heads 1a and 1b
Height can be controlled.

If the electromagnetic force fa ₁ is set to be equal to fa ₂ , the RY-direction moment due to the electromagnetic force hardly acts (fa ₁ · r-fa ₂ · r =
0). The center of rotation in the RY direction is near the center of gravity of the movable member 8a.

Next, a specific operation of the tracking actuator of the rotary head type magnetic recording / reproducing apparatus of this embodiment at the time of recording or reproducing a signal of the tracking actuator will be described.

[At the time of signal reproduction] Recording tracks on the magnetic tape and the magnetic heads 1a and 1a scanning the recording tracks
The position relative to b is always detected by a pilot signal or the like. The height of the magnetic heads 1a and 1b is constantly controlled based on this information. That is, a dynamic tracking operation is performed.

[At the time of signal recording] Signal recording is performed by one of the following methods (1) and (2).

(1) The dynamic tracking operation is not performed, and the magnetic heads 1a and 1b are
b is supported by the rigidity.

(2) The absolute height of the magnetic head 1a or 1b during signal recording is constantly detected by the magnetic head height detection sensor, and the magnetic head 1a, 1b
The height of 1b is always controlled. That is, a dynamic tracking operation is performed. As the magnetic head height detection sensor, a known sensor such as a capacitance type, an eddy current type, or an optical type may be used.

As described above, in the rotary head type magnetic recording / reproducing apparatus of this embodiment, as shown in FIG. 5, the first and second coils 1 are opposed to both side surfaces 7a ₁ and 7a ₂ of the permanent magnet 7a.
5a and 15b are provided. For this reason, the permanent magnet 7
A driving force by an electromagnetic force can be applied to both side surfaces 7a ₁ and 7a ₂ of “a”. Therefore, a larger driving force can be obtained than in the conventional example in which the driving force is applied only to one surface of the permanent magnets 807a and 807b as shown in FIG.
Since the driving force is large, even if the rigidity of the parallel leaf springs 5a and 5b is increased, the parallel leaf springs 5a and 5b can be sufficiently displaced. Therefore, it is possible to increase the first-order and higher-order resonance frequencies.

Since the rigidity of the parallel leaf springs 5a and 5b can be increased, the vibration of the magnetic heads 1a and 1b during recording can be suppressed.

The yoke 13 constituting the magnetic circuit is disposed on the fixed drum 30. Therefore, as shown in FIG. 22, the portions 813a and 813b of the yoke are
In the present embodiment, the mass of the movable portions of the parallel leaf springs 5a and 5b can be reduced as compared with the conventional example included in 8a and 808b. Therefore, it is possible to increase the primary and higher order resonance frequencies.

Further, both side surfaces 7a ₁ , 7a of the permanent magnet 7a
₂ , a driving force can be applied. Therefore, FIG.
By setting the driving forces fa ₁ and fa ₂ to be equal as shown in FIG. 7, the RY direction moment is prevented from acting on the movable member 8a as described above. For this reason, the peak value of the gain at the resonance point in the RY direction can be reduced.

FIG. 9 is a graph showing the relationship between the frequency and the gain in the vibration characteristics of the magnetic head 1a. FIG. 9 shows the relationship between the supply current (input) to the drive coils 15a and 15b in the Z direction in FIG. The frequency response of displacement (output) is shown. Note that the solid line in FIG. 9 is the gain-frequency curve of the present embodiment, and the one-dot chain line is the gain-frequency curve of the conventional example.

Referring to FIG. 9, as described above, in the rotary head type magnetic recording / reproducing apparatus of this embodiment, the secondary resonance frequency can be made higher than in the conventional example, and the gain at the secondary resonance point can be increased. The peak value can be lowered. Therefore, in the present embodiment, the gain intersection frequency of the open-loop transfer function in the closed-loop control can be set high, and accordingly, the response frequency of dynamic tracking can be increased. Therefore, even when the rotational speed of the drum is further increased, the magnetic head can follow the track bend during signal reproduction, and the responsiveness of the dynamic tracking operation is improved.

Embodiment 2 FIG. 10 is a sectional view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to Embodiment 2 of the present invention.
Is a cross section corresponding to the cross section of FIG.

Referring to FIG. 10, in the rotary head type magnetic recording / reproducing apparatus 200 of the present embodiment, as compared with the first embodiment,
The configurations of the movable member 108a and the yoke 113 are different.
That is, the movable member 108a includes the permanent magnet 7a, the shield plate 106a made of a soft magnetic material, and the spacer 9a made of a non-magnetic material.
And a three-layer laminated structure. The movable member 108b
The same applies to. Also, the concave side surface 1 of the yoke 113
13a and 113b extend to a height facing the shield plates 106a and 106b.

The spacers 9a and 9b are necessary in terms of space, as described above, and may not be provided in some cases. The other configuration is almost the same as that of the first embodiment. Therefore, the same components are denoted by the same reference symbols, and description thereof is omitted.

In this embodiment, the shield plate 106
a and 106b absorb the leakage magnetic flux of the magnetic circuit including the permanent magnets 7a and 7b and the yoke 113. In particular, pole 7a shield plate 106a is from the pole 7a ₁ of permanent magnet 7a
Absorbs the magnetic flux that jumps directly into ₂ . Therefore, the above-described leakage magnetic flux does not reach the magnetic head 1a, and good recording / reproducing characteristics can be maintained.

The operation of the shield plate 106b is the same as described above. Third Embodiment FIG. 11 is a plan view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to a third embodiment of the present invention.
Corresponds to the plan view of FIG. FIG. 12 is a cross-sectional view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to the third embodiment of the present invention, and is a cross-section corresponding to a cross-section taken along line DD of FIG.

Referring to FIGS. 11 and 12, the rotary head type magnetic recording / reproducing apparatus 300 of the present embodiment is different from Embodiment 1 in the configuration of the yoke 213. That is, the first embodiment
In this embodiment, the yoke 13 is formed in an annular shape over the entire circumference, but in this embodiment, the yoke 213 has an arc shape.

The remaining structure is almost the same as that of the first embodiment, and therefore, the same components are denoted by the same reference characters and description thereof will not be repeated.

Referring to FIGS. 11 and 12, two magnetic heads 1a and 1b (illustration of magnetic head 1b is omitted) attached to first leaf spring 5a have movable section 8a and movable section 8a.
8b. That is, the two magnetic heads 1a and 1b are arranged at positions different from each other by 180 ° about the shaft 21. Drum 30
The winding angle of the magnetic tape 90 around 0 is 180 °. Here, points J and K correspond to the magnetic tape 9 on the drum.
0 represents the end point of the wound portion.

When the magnetic heads 1a and 1b rotate in the R direction together with the rotary drum 40, they enter the magnetic tape 90 at the point J and retreat from the magnetic tape 90 at the point K. At the same time as the magnetic head 1a leaves the magnetic tape 90, the magnetic head 1b enters the magnetic tape 90. That is, both side surfaces 213a and 213b of the yoke 213 are connected to the magnetic head 1a.
There during scanning the magnetic tape 90 to the point J~ point K is arranged so as to face the magnetic poles 7a _1, 7a ₂ of at least the permanent magnet 7a. Therefore, while the magnetic head 1a is scanning the magnetic tape 90, the same dynamic tracking operation as in the first and second embodiments can be performed. The same applies to the magnetic head 1b.

In this embodiment, the first and second drive coils 15a and 15b have an annular shape.
As shown in FIG. 3, it may be wound around the wall surface of the yoke 213.

In this embodiment, the wall surface 2 of the yoke 213
13a, was an arc shape having the same center angle theta ₁ Both 213b, it is not always necessary that, for example, in one wall arcuate and the other wall may be a ring.

The wall surfaces 213a, 213 of the yoke 213
b may have a shape consisting of a plurality of arcs instead of one arc each.

As described above, in the rotary head type magnetic recording / reproducing apparatus of this embodiment, the yoke 213 has an arc shape, has a ring shape like the yoke 13 of the first embodiment, and is provided over the entire circumference. Do not mean. For this reason, compared with the first embodiment, in the present embodiment, a space is obtained in the fixed drum 30 by the amount of omitting the yoke. In this space, a sensor for detecting the height of the magnetic head and various wiring terminals can be arranged with a margin. In this way, by using this space, it is possible to achieve more functions and higher functions while maintaining the dimensions.

Embodiment 4 FIG. 14 is a plan view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to Embodiment 4 of the present invention.
1 corresponds to the plan view of FIG. In the present embodiment, the configuration of the yoke 313 is different from the configuration of the third embodiment. In addition,
The other configuration is almost the same as that of the third embodiment. Therefore, the same components are denoted by the same reference symbols, and description thereof will be omitted.

Two magnetic heads 1 not shown here
Similar to the third embodiment, a and 1b are arranged at positions different from each other by 180 ° about the shaft 21. The winding angle of the magnetic tape 90 around the drum is 90 °.

Also in this embodiment, while either of the magnetic heads 1a or 1b scans the magnetic tape 90, the permanent magnet of the movable portion that scans the magnetic tape 90 contacts the wall surface of the yoke. opposite. Therefore, Embodiment 3
Similarly to the above, the dynamic tracking operation can be performed while the magnetic head 1a is scanning the magnetic tape 90.

The two magnetic heads 1 facing each other
When a and 1b are at the rotational positions of the points R1 and R2, the permanent magnets 7a supported by the parallel leaf springs 5a and 5b,
7b does not face the wall surface of the yoke 313. Therefore, when the rotary head type magnetic recording / reproducing apparatus is assembled at this position, the permanent magnets 7a and 7b
Can be completely prevented from being attracted to the wall surface, and the assembly becomes easy.

Embodiment 5 FIG. 15 is a plan view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to Embodiment 5 of the present invention.
Corresponds to the plan view of FIG. 16 and 17 are cross-sectional views of a rotary head type magnetic recording / reproducing apparatus according to the fifth embodiment of the present invention, which are cross sections corresponding to the cross section taken along line EE and line FF in FIG. 15, respectively. is there. FIG. 18 is a schematic perspective view of a parallel leaf spring mounted on a rotary head type magnetic recording / reproducing apparatus according to Embodiment 5 of the present invention and members sandwiched therebetween.

Referring mainly to FIGS. 15 and 18, in the rotary head type magnetic recording / reproducing apparatus 500 of the present embodiment, as compared with the second embodiment, the member sandwiched between the parallel leaf springs and the adjusting screw 447 Is different.

That is, the parallel leaf springs 5a and 5b are connected to the fixed members 411a and 411b and the movable members 108a and 108b.
In addition, the four head height adjusting members 412a, 412
a, 412b, and 412b. The head height adjusting members 412a and 412a are respectively provided with fixing members 411.
b and the movable member 108a, and between the fixed member 411a and the movable member 108a. The head height adjusting members 412b and 412b are respectively fixed to the fixing members 411.
b and the movable member 108b, and between the fixed member 411a and the movable member 108b.

Referring mainly to FIGS. 16 and 17, parallel leaf springs 5a and 5b sandwiching the head height adjusting member and the like will be described.
Is attached to the rotating drum 40 at a position where the fixing members 411a and 411b are attached. In this state, four adjusting screws 447 are screwed into the screw holes 40a of the rotary drum 40 so that each position of the leaf spring 5a to which the head height adjusting member is attached can be pressed from above in the figure.

Here, as shown in FIG. 18, the leaf springs 5a,
The portion between the movable member 5b and the head height adjusting member
a _1, 5b represents _one consisting symbol to represent the portion between the head and the height adjusting member and the fixed member 5a _2, 5b ₂ becomes symbols. Also, expressed as parallel leaf springs 4a becomes a symbol composed of a plate spring 5a ₁ and 5b ₁ described above, the parallel plate springs constituted by a plate spring 5a ₂ and 5b ₂ 4
It is represented by the symbol b.

In the above-described configuration, the movable member 108a has the fixed members 411a and 411b as fixed ends, and the movable members 108a can move the two sets of parallel leaf springs 4b and 4a in a coupled state via the head height adjusting members 412a and 412a. Department. The same applies to the movable member 108b.

Here, by making the peripheral length of the parallel leaf spring 4b shorter than the peripheral length of the parallel leaf spring 4a,
The rigidity of b is set to be sufficiently higher than that of the parallel leaf spring 4a. The rigidity of the parallel leaf spring 4b may be increased by making the width of the parallel leaf spring 4b in the radial direction larger than the width of the parallel leaf spring 4a. Also, four head height adjusting members 412a, 412a, 412b, 412b
Is designed to use a lightweight material such as aluminum or to devise its shape so that its mass is as small as possible.

Next, a description will be given of a method of adjusting the absolute height of the magnetic head when assembling the rotary head type magnetic recording / reproducing apparatus in this embodiment. Here, only the method of adjusting the magnetic head 1a will be described, but the same applies to the magnetic head 1b.

Referring to FIG. 17, in the process of assembling the apparatus described in the first embodiment, the rotating drum 40
Are fixed, the head height adjusting members 412a and 412a are pressed downward by the head height adjusting screw 447 via the leaf spring 5a while controlling the height of the magnetic head 1a. At this time, no current is supplied to the drive coils 15a and 15b. Thereby, the head height adjusting member 412a,
Since the movable member 108a moves downward in the drawing together with 412a, the absolute height of the magnetic head 1a can be adjusted.

After the height adjustment of the magnetic heads 1a and 1b, the assembly is completed in the same manner as described above. The absolute height of the magnetic heads 1a and 1b before the height adjustment is set so as to be higher than the reference height.

Next, the basic operation of the tracking actuator of this embodiment will be described. Here, only the operation of the magnetic head 1a will be described.
The same applies to b.

When the driving force (fa ₁ , fa ₂ ) described with reference to FIG. 8 in the first embodiment acts on the permanent magnet 7a, the movable member 108a and the magnetic head 1a move vertically about the reference height. Displace.

When the driving force acts upward in the figure, the head height adjusting members 412a, 412a,
The movable member 108a is displaced upward in the drawing to a position where the reaction force of the parallel leaf spring 4a having the fixed end 12a is balanced with the driving force.

When the driving force acts downward, the fixed members 411a and 411b are used as fixed ends, and the parallel plate spring 4b and the parallel plate spring 4a which are coupled with the head height adjusting members 412a and 412a interposed therebetween. The movable member 108a is displaced downward in the figure until the reaction force balances with the driving force. Here, the rigidity of the parallel leaf spring 4b is sufficiently higher than the rigidity of the parallel leaf spring 4a.
a and 412a are hardly displaced and do not cause unnecessary vibration.

The specific operation of the tracking actuator according to the present embodiment when recording or reproducing a signal is as follows.
The description is omitted because it is almost the same as in the first embodiment.

As described above, in this embodiment, the dynamic tracking operation centering on the reference height of the magnetic heads 1a and 1b can be performed at the time of signal reproduction.

At the time of signal recording, the magnetic heads 1a, 1b
The dynamic tracking operation centering on the reference height or the signal recording at the reference height becomes possible.

Adjustment of the absolute height of the magnetic heads 1a and 1b has already been performed at the time of assembling the apparatus. Therefore, it is not necessary to supply a DC bias current to the drive coil when recording or reproducing a signal to adjust the absolute height of the magnetic heads 1a and 1b.

Since the movable members 108a and 108b are not directly restricted by the head height adjusting screw 447,
The displacement of the magnetic heads 1a and 1b during dynamic tracking is not restricted.

Embodiment 6 In Embodiment 5 described above, the magnetic head 1a,
The absolute height of 1b is set to the reference height. In this embodiment, furthermore, for example, a relative height shift between the two magnetic heads 1a and 1b due to a change with time can be adjusted.

FIG . 19 shows the rotation in the sixth embodiment of the present invention.
Relative height of magnetic head in head type magnetic recording / reproducing device
FIG. 4 is a schematic partial cross-sectional view showing a state in which a shift has occurred. Figure
Referring to FIG. 19, the configuration of the rotary head type magnetic recording / reproducing apparatus of the present embodiment is different from Embodiment 5 in the directions of magnetization of the two permanent magnets. For example, one permanent magnet 50
7a is one side 507a near the axis AA of the shaft.
₁ is the N pole, while the other side 507a ₂ are magnetized such that S pole. Further, the permanent magnet 507b is connected to the axis A of the shaft.
One side surface 507b ₁ S pole closer to -A line, the other side surface 50
7b ₂ is magnetized so as to be an N pole.

The remaining structure is almost the same as that of the fifth embodiment, and therefore the same components are denoted by the same reference characters and description thereof will not be repeated.

Next, the basic operation of the tracking actuator of this embodiment will be described.

As described above, in this embodiment, since the two permanent magnets 507a and 507b have the opposite magnetization directions, when the same current is supplied to the drive coils 15a and 15b, the magnetic head Driving forces fa and fb of the same magnitude and opposite directions act on 1a and 1b, respectively. As a result, the magnetic heads 1a and 1b are displaced in opposite directions.

FIG. 20 is a graph showing the relationship between the drive current and the displacement of the magnetic head. Referring to FIG. 20, the horizontal axis represents the drive current, which represents the current supplied to the two drive coils. The direction shown in FIG. 19 is positive, and the opposite direction is negative. The vertical axis indicates the displacement of the magnetic heads 1a and 1b, with the reference height of the magnetic head being the origin, the upward direction in FIG. 19 is positive, and the downward direction in FIG. 19 is negative. FIG. 20 shows the magnetic heads 1a and 1a when no current is supplied to the drive coil.
The case where the absolute height of b deviates from the reference height is shown.

The absolute height of the magnetic heads 1a and 1b is adjusted to the reference height at the time of assembling the apparatus as described in the fifth embodiment, and is shifted, for example, by a change with time thereafter. Such a shift in the height of the magnetic head due to such a change over time occurs due to, for example, a change in the contact state between the head height adjustment member and the head height adjustment screw, a distortion due to the repetitive operation of the parallel leaf spring, and the like.

Referring to FIG. 20, magnetic heads 1a and 1b
Has an absolute height shift of Xa and Xb, respectively. Therefore, δ = | Xa−
Xb | is generated. Where I = i
When a DC bias current is supplied, the magnetic heads 1a and 1b are both displaced to an absolute height of Xab = (Xa + Xb) / 2, and the relative height is adjusted.

Since Xa and Xb are on the order of at most several μm, the absolute height deviation of the magnetic heads 1a and 1b of Xab is within the allowable range of the tape format.

The above-described DC bias current need only absorb the relative height error between the magnetic heads 1a and 1b due to, for example, aging, and does not need to absorb all the errors due to the mounting of the magnetic head.

The relative height error between the magnetic heads 1a and 1b is detected indirectly by detecting the absolute height of the magnetic heads 1a and 1b, for example. The absolute height detection of the magnetic heads 1a and 1b
It may be performed once per rotation of a and 1b, and at least one sensor may be arranged. The sensor may be located on the fixed drum side, on the rotating drum side, or outside the drum device. As a detection method, a known method such as a capacitance method, an eddy current method, or an optical method may be used. Good.

As an example of the above-mentioned sensor, FIG. 16 shows an example in which a capacitance sensor 445 is arranged on the fixed drum 30 side. The capacitance sensor 445 is opposed to the leaf spring 5b and detects the capacitance between them. The height of the magnetic heads 1a and 1b can be detected by detecting the capacitance of the leaf spring 5b at the portion where the magnetic heads 1a and 1b are located.

Note that the leaf spring 5b is made of a conductive material such as phosphor bronze. As described above, in the rotary head type magnetic recording / reproducing apparatus of the present embodiment, the relative height deviation between the two sets of magnetic heads can also be adjusted.

The adjustment amount of the relative height of the magnetic head is, for example, only due to a change with time. Therefore, the amount of DC bias current supplied to the drive coil, the amount of displacement to be ensured by the actuator, and the absolute height of the magnetic head It is much smaller than when both the relative height is adjusted. This is because the initial absolute height of the magnetic head is already adjusted at the time of assembling the apparatus.

Embodiment 7 In Embodiments 1 to 6, the first and second leaf springs 5a and 5b constituting the parallel leaf spring are both of the same ring shape. On the other hand, in the present embodiment, the first leaf spring 605a and the second leaf spring
05b has a different shape.

FIG. 21 is a perspective view schematically showing a configuration of a parallel leaf spring mounted on a rotary head type magnetic recording / reproducing apparatus according to Embodiment 7 of the present invention and members sandwiched therebetween. Referring to FIG. 21, in the present embodiment, a second leaf spring 605b subject to space limitation by the yoke
Has the same shape as the above-described first to sixth embodiments. On the other hand, the first leaf spring 605a with less space restriction has a shape whose width in the radial direction is wider than that of the first leaf springs of the above-described first to sixth embodiments. .

The parallel leaf springs 605a, 605b
The fixing members 611a and 611b and the head height adjusting members 612a and 612b held by the first leaf spring 6
The portion joined to the second leaf spring 605b has a relatively large shape, and the portion joined to the second leaf spring 605b has a relatively small shape.

As described above, in this embodiment, the width in the radial direction of the first leaf spring 605a constituting the parallel leaf spring is wider than the width in the radial direction of the second leaf spring 605b. Therefore, the head base can be easily mounted on the first leaf spring 605a, and the movable member 108 can be easily mounted.
In particular, it is possible to effectively suppress the vibration of the a and 108b especially around the X axis and the Y axis.

The shapes of the first leaf spring 605a and the second leaf spring 605b are not limited to those described above as long as they are based on the basic concept of the present invention, and any shapes can be adopted.

[0167]

In the rotary head type magnetic recording / reproducing apparatus according to the first to third aspects, the first and second coils are provided so as to face both sides of the permanent magnet. A driving force can be applied to the surface. Therefore, even if the rigidity of the parallel leaf spring is increased, the parallel leaf spring can be sufficiently displaced, and the primary and higher order resonance frequencies can be increased, so that the responsiveness of dynamic tracking is improved. .

Further, since the rigidity of the leaf spring can be increased, the vibration of the magnetic head during recording can be suppressed.

Further, since the yoke constituting the magnetic circuit is arranged on the fixed drum, the mass of the movable portion of the parallel leaf spring can be reduced. Therefore, it is possible to increase the primary and higher order resonance frequencies, and the responsiveness of dynamic tracking is further improved.

Further, since a driving force can be applied to both side surfaces of the permanent magnet, a rotational moment is not applied to the movable portion of the parallel leaf spring. Therefore,
The peak value of the gain at the rotational resonance can be reduced, and the responsiveness of the dynamic tracking is further improved.

In the rotary head type magnetic recording / reproducing apparatus according to the fourth aspect, the permanent magnet is attached to the leaf spring via a shield plate made of a soft magnetic material. Therefore,
The magnetic flux leaked from the permanent magnet is absorbed by the shield plate, and the magnetic flux does not affect the magnetic head.

In the rotary head type magnetic recording / reproducing apparatus according to the fifth and sixth aspects, the yoke has an arc shape,
It is not provided over the entire circumference. Thus, compared to the case where the yoke is provided over the entire circumference, a space is obtained in the fixed drum by the amount of the yoke being omitted. Therefore, by using this space,
Multi-functionality and high functionality can be achieved while maintaining the dimensions.

In the rotary head type magnetic recording / reproducing apparatus according to the seventh to tenth aspects, the absolute height of the magnetic head at the time of assembling the drum device can be adjusted by pressing a predetermined position of the leaf spring with the leaf spring pressing member. It becomes possible.

In the rotary head type magnetic recording / reproducing apparatus according to the eleventh aspect, the first leaf spring constituting the parallel leaf spring is wider in the radial direction than the second leaf spring. Therefore, when assembling the drum device, it becomes easy to attach the magnetic head to the first leaf spring. Further, since the width of the first leaf spring in the radial direction is wide, the rigidity of the first leaf spring is improved, and the vibration of the magnetic head can be suppressed.

In the rotating head type magnetic recording / reproducing apparatus according to the twelfth aspect, the magnetization directions of the two permanent magnets are opposite. Therefore, by supplying a DC bias current to the drive coil, the magnetic head group at a relatively high position is displaced downward, and the magnetic head group at a relatively low position is displaced upward, so that two sets of magnetic heads are displaced. The relative height of the head group can be adjusted.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a configuration of a rotary head type magnetic recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a state where a rotary drum, a shaft, and a motor are removed from FIG. 1;

FIG. 3 is a schematic plan view seen from the direction of arrow X in FIG. 2;

FIG. 4 is a schematic plan view showing a configuration in which a magnetic head, a head base, and a first leaf spring are omitted from FIG. 3;

FIG. 5 is a schematic sectional view corresponding to a section taken along line BB in FIGS. 3 and 4 of the rotary head type magnetic recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 6 is a schematic sectional view corresponding to a section taken along line CC of FIGS. 3 and 4 of the rotary head type magnetic recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 7 is a perspective view schematically showing a configuration of a parallel leaf spring mounted on the rotary head type magnetic recording and reproducing apparatus according to the first embodiment of the present invention and members sandwiched therebetween.

FIG. 8 is a schematic sectional view showing an enlarged part of FIG. 5;

FIG. 9 is a graph showing a relationship between a gain and a frequency in comparison between the present invention and a conventional example.

FIG. 10 is a schematic sectional view corresponding to FIG. 5 of a rotary head type magnetic recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 11 is a schematic plan view corresponding to FIG. 4 of a rotary head type magnetic recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 12 is a schematic sectional view corresponding to a section taken along line DD of FIG. 11 of the rotary head type magnetic recording / reproducing apparatus according to the third embodiment of the present invention.

FIG. 13 is a schematic plan view showing a configuration when a coil is arranged so as to surround a side wall of the yoke.

FIG. 14 is a schematic plan view corresponding to FIG. 4 of a rotary head type magnetic recording / reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 15 is a schematic plan view corresponding to FIG. 4 of a rotary head type magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention.

FIG. 16 is a schematic sectional view showing a rotary head type magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention, corresponding to a section taken along line EE of FIG. 15;

FIG. 17 is a schematic sectional view showing a rotary head type magnetic recording and reproducing apparatus according to a fifth embodiment of the present invention, corresponding to a section taken along line FF of FIG. 15;

FIG. 18 is a perspective view schematically showing a configuration of a parallel leaf spring mounted on a rotary head type magnetic recording / reproducing apparatus according to a fifth embodiment of the present invention and members sandwiched therebetween.

FIG. 19 is a schematic partial sectional view showing a state in which a relative height shift of a magnetic head has occurred in a rotary head type magnetic recording / reproducing apparatus according to a sixth embodiment of the present invention.

FIG. 20 is a graph showing a relationship between a drive current and a displacement of a magnetic head.

FIG. 21 is a perspective view schematically showing a configuration of a parallel leaf spring mounted on a rotary head type magnetic recording / reproducing apparatus according to a seventh embodiment of the present invention and members sandwiched therebetween.

FIG. 22 is a sectional view schematically showing a configuration of a conventional rotary head type magnetic recording / reproducing apparatus.

FIG. 23 is an exploded perspective view schematically showing a configuration of a conventional rotary head type magnetic recording / reproducing apparatus.

FIG. 24 is a graph showing the relationship between frequency and gain.

FIG. 25 is a graph showing the relationship between frequency and phase.

FIG. 26 is a control block diagram by closed loop control.

FIG. 27 is a graph showing the relationship between the frequency of the open-loop transfer function and the gain in the block diagram of FIG. 26;

FIG. 28 is a graph showing the relationship between frequency and phase.

FIG. 29 is a graph for explaining that the gain intersection frequency increases when the secondary resonance frequency increases.

FIG. 30 is a graph for explaining that the gain intersection frequency increases when the peak value at the secondary resonance point decreases.

[Explanation of symbols]

 1a, 1b Magnetic head 3a, 3b Head base 5a, 5b Parallel leaf spring 7a, 7b Permanent magnet 9a, 9b Spacer 11a, 11b Fixed member 13 Yoke 15a, 15b Drive coil 30 Fixed drum 40 Rotary drum

Continuation of the front page (56) References JP-A-57-33426 (JP, A) JP-A-60-107722 (JP, A) JP-A-61-246911 (JP, A) JP-A-4-286711 (JP) JP-A-5-182165 (JP, A) JP-A-7-65341 (JP, A) European Patent Application Publication 552970 (EP, A1) (58) Fields investigated (Int. Cl. ⁷ , DB G11B 5/52 G11B 5/588

Claims (12)

(57) [Claims] A fixed body having an axis; a rotating body including a rotating drum supported by the fixed drum so as to be rotatable about the axis; a movable part and a fixed part; Comprises first and second leaf springs in which the fixed portion is supported by the rotating body so that the first and second leaf springs can be displaced in a direction along the axis, wherein the first and second leaf springs have a predetermined distance from each other. A magnetic head fixed to the movable portion of the first leaf spring; a movable portion of the first leaf spring; and a movable portion of the second leaf spring. A movable member including a permanent magnet having first and second magnetic poles sandwiched between the first and second side surfaces, wherein the first side surface has a predetermined position with the first magnetic pole of the permanent magnet. The second side faces in front of the permanent magnet so as to face each other with a space therebetween. 2nd
A yoke disposed in said fixed drum so as to face each other with the magnetic poles with a predetermined space, the fixedly installed so as to face each other with the first magnetic pole and the predetermined space of the permanent magnet A first coil, and a second coil fixedly provided to face the second magnetic pole of the permanent magnet with a predetermined space therebetween, and energizing the first and second coils. The permanent magnet and the first and second coils are arranged so that the magnetic head moves in a direction along the axis. 2. The first and second leaf springs have a configuration of a support beam at both ends, and both ends of the first and second leaf springs become the fixing portions, and the first and second leaf springs are provided. 2. The rotary head type magnetic recording / reproducing apparatus according to claim 1, wherein a central portion sandwiched between the both ends of the leaf spring is the movable portion. 3. The rotary head type magnetic recording / reproducing apparatus according to claim 1, wherein the yoke has a ring shape centered on the axis. 4. The movable member has a shield plate made of a soft magnetic material, and the first leaf spring has a first surface and a second surface located on the back surface of the first surface. The magnetic head is supported on the first surface of the first leaf spring, and the permanent magnet is supported on the second surface of the first leaf spring via the shield plate. The rotary head type magnetic recording / reproducing apparatus according to claim 1, wherein 5. The rotating head type magnetic recording / reproducing apparatus according to claim 1, wherein said yoke has an arc shape centered on said axis. 6. A section in which a magnetic tape is wound around the outer peripheral surfaces of the rotating drum and the fixed drum, and during one rotation of the magnetic head, in a section where the magnetic head scans the magnetic tape, A central angle of the yoke having an arc shape is set such that at least each of the first and second magnetic poles of the permanent magnet faces the first and second side surfaces of the yoke with a predetermined space therebetween. The rotary head type magnetic recording / reproducing apparatus according to claim 5, wherein 7. A leaf spring press supported by the rotating body so as to be able to press an intermediate portion between the movable portion and the fixed portion of the first or second leaf spring in a direction along the axis. The rotary head according to claim 1, further comprising: a member; and a head height adjusting member sandwiched between the intermediate portion of the first leaf spring and the intermediate portion of the second leaf spring. Type magnetic recording and reproducing device. 8. A fixed drum having an axis as a center, a rotating body including a rotary drum supported on the fixed drum so as to be rotatable about the axis, a movable section and a fixed section, The fixed portion includes first and second leaf springs supported by the rotating body so that the movable portion can be displaced in a direction along the axis. The first and second leaf springs are mutually fixed. A magnetic head fixed to the movable part of the first leaf spring, and a movable part of the first leaf spring and a movable part of the second leaf spring. A movable member sandwiched between the first and second leaf springs; a driving unit for displacing the movable section of the first and second leaf springs in a direction along the axis; and a movable section of the first or second leaf spring. An intermediate portion between the fixing portion and the fixing portion can be pressed in a direction along the axis. A leaf spring pressing member supported by the rotating body; and a head height adjusting member sandwiched between the intermediate portion of the first leaf spring and the intermediate portion of the second leaf spring. Also, a rotating head type magnetic recording / reproducing device. 9. A distance between the intermediate portion and the fixed portion of the leaf spring pressed by the leaf spring pressing member is shorter than a distance between the intermediate portion and the movable portion. 9. A rotary head type magnetic recording / reproducing apparatus according to item 8. 10. A radial width of a rotation surface around the axis of a portion between the intermediate portion and the fixed portion of the leaf spring pressed by the leaf spring pressing member is equal to the width of the intermediate portion. 9. The rotary head type magnetic recording / reproducing apparatus according to claim 7, wherein the width between the movable part and the movable part is wider than the radial width. 11. The rotation according to claim 1, wherein a width of the first leaf spring in a radial direction of a rotation surface around the axis is larger than a radial width of the second leaf spring. Head type magnetic recording / reproducing device. 12. A magnetic head group including one or a plurality of the magnetic heads and two sets of the movable member including the permanent magnets. Each one of the two sets of the magnetic head groups includes: The two permanent magnets are provided corresponding to each one of the two movable members, and both of the two permanent magnets have a first magnetic pole near the axis and a first magnetic pole far from the axis. When the second magnetic pole is used, the first magnetic pole of the permanent magnet corresponding to one magnetic head group and the first magnetic pole of the permanent magnet corresponding to the other magnetic head group have different polarities from each other. So that
The second magnetic pole of the permanent magnet corresponding to one of the magnetic head groups and the second magnetic pole of the permanent magnet corresponding to the other magnetic head group have different polarities from each other. A set of permanent magnets is configured, and by energizing the first and second coils,
2. The rotary head type magnetic recording / reproducing apparatus according to claim 1, wherein two sets of said permanent magnets and said first and second coils are arranged such that sets of said magnetic head groups are displaced in opposite directions. .